Control means for air conditioning apparatus



Filed! &me 3, 1946 CONTROL MEANS FOR AIR CONDITIONIN& APPARATUS 2Shets-Shee' 1 III////!III/fil ll l /ENY 0. Mem /2 meme Dec. 7, 1948. AH. o. kRKPATRcK I & 5 r

CONTROL HEARS FOR AIR ONDITIONING APPARATUS A Filed June 3, ;946 2Shets-Sheat -2 MEANS FOR AIR CONDITIONING i APPABATUS Henry O.Kirkpatriok, Detroit, Mish., or to Advance Manuiaoturing, Inc.. Detroit,Mich., a.

corporation ot Michigan CONTEOL 'Application Jme 3, 1946, Serial No.673,991 8 Clalms. (CL 62-8) This invention relates to air conditioningapparatus and refers more particularly to improvements in the controlmeans for apparatus o! the type constructed to either cool or heat theatmosphere within an enclosure.

Although the air conditioning apparatus including the control system forOperating the severa! instrumentalities of' the apparatus may be used inpractically any installation where it is desired to selectively cool aheat the atmosphere within an enclosure, nevertheless, it findsparticular utllity when employed for the p rpose of air conditioningtruck bodie's, railway cars, buses, trailers or aircraft. In most ofthese applications, the refrigerant compressor of the apparatus isoperated by an internal combustion engine and valves are provided forchanging the cycle of operation of the appa'ratus. Also, fans orequivalent air circulating means are usually provided for forcing airthrough the condenser and evaporator or beat exchange unit.

With the above in View, it is one of the objects of this invention toprovide an electrical control system capable of being operated from aremote point to first, start and stop the internal combustion engine;second, operate the valves to secure either cooling or heating of theatmosphere within the enclosure; thircl, control the operation of thefans or equivalent air circulating means; and fourth, clefrost theevaporator or heat exchange unit at any time during the cooling cycleAnother object of this invention is to provide an electric controlcircuit embodying a safety switch responslve to abnormal pressures inthe refrigerant condenser to open the ignition circuit and stop theengine.

Stiil another ohj ect of this invention is to provide an electriccontrol circuit having a switch responsive to starting of the internalcombust'on engine to open the Starter switch.

The foregoing as well as other objects will be mad more apparent as thisdescription proceeds, especially when considered in connection with theaccompanying drawing, wherein:

"figure is a semi-d'agrammatic View of air conditioning apparatusembodying the features of this inventicn;

Figura` 2 is a wir-ing diagram of the control circuit; and

of the master phere within an enclosure to maintain a predeterminedtemperature within the enclosure regardless o! the temperature oi theatmosphere outside of the enclosure. Briefly, the air conditioningapparatus comprises a. retrigerant compressor ll, a prime mover in theform of an internal combustion engine z for Operating the compressor, arefrigerant condenser I 3, a. heat exchange unit I 4, and an evaporator15.

The heat exchange unit I 4 may be of any suitable construction capableof efliciently exchanging heat with the surrounding atmosphere and issuitably supported in an enclosure IS' containing the atmosphere whichit is desired to main-- tain at a, predetermined temperature. The air oratmosphere within the enclosure is circulated through the heat exchangeunit id by a fan !6 supported at one side of the heat exchange unit. anddriven by an electric motor H.

The compressor H. internal combustion ngine !2, condenser 13 andevaporator !5 are suitably supported within a compartment s having anentrant 'opening for air l9 through the bottom wall thereof. One endwall zo of the compartment I8 is formed with an opening 2! therethroughand the passage of air through this open ing is controlled by a closure22 comprising a plurality of louvres 23. The louvres are operativelyconnected to a control arm 24 pivotally supported on the wall 20 of theclosure for convenient manipulation. The louvres 23 are shown in theiropen positions in Figure 1 of the drawing and may be readily closed bymerely swinging the arni 24 to its dotted line position shown in Figure1 of the drawings. The opposite end wall 25 of the compartment IS has anopening 28 therethrough, and the passage of air through the opening 25is controlled by a closure 21 comprising a plurality of louvres 28normally held in their open positions by means of a spring 29. A controlarm 38 is suitably pivotally supported on the end wall 25 for convenientmanipulation, and is operatively connected to the louvres 253 forclosing the same. A second opening 3! is formed in the end wall 25 abovethe opening 25, and this opening communicates with an air duct ?12arranged adjacent the internal combustion engine az and surroun ing theexhaust conduit 33 for the engine. An opening 34 is formed at the bottomof the delivery end portion 35 oi' the air duet, and the passage of airthrough this opening is controlled by a damper 36, which also serves toclose the opening si when it is swung to its open position relativetothe opening 34. The damper st is operetively connected to the arm foroperation by the letter. The arrangement is such that when the arm 30 isin its full line position shown in Figure 1 of the drawing, the danper36 closes the opening 34 and the louvres 28 are in their open positions.On the other hand when the arm 30 is swung to its dotted line positionto close the louvres 28, the damper 36 is swung upwardly to open theopening 34 and to close the opening 3l.

The rerigerant condenser 13 may be of any suitable construction capableof emciently condensing the reirigerant in the compartment a immediately'adjacent the opening 2i. Air is drawn into the compartment l8 throughthe opening !9 and is forced through the condenser !3 out of thecompartment by a fan 31. The fan 31 is suitably supported at the innerside of the condenser !3 and is driven by an electric motor 38. Theupper end of the condenser l3 is connected to the high pressure side ofthe compressor li by a conduit 39, and the lower end of the condenser.l3 is connected to a receiver tank 40. The receiver tank 40 is suitablysupported in the compartment !3 below the condenser i3 and is connectedto the receiving or upper end of the heat exchange unit l4 by a conduit41. An expansion valve 42 is connected in the conduit 4i adjacent thereceiving end of the heat exchange unit i4 in accordance withconventional practice.

The expansion valve 4 is bypassed by a conduit 43 and a valve 44 issuitably connected in the bypass. The lower or return end of the heatexchange unit l I is connected to an -auxiliary receiver tank 44 by aconduit 45. The auxiliary receiver tank 44 'is suitably supported in thecompartment |8 and is connected to the low pressure sides of thecompressor il by a conduit 46. A control valve 41 is connected into theconduit 46 between .the receiver tank 44 and compressor ll.

The evaporator |5 may also be of any accepted design and is supported inthe -compartment l8 adjacent the opening 26 through the wall 25 of thecompartment. The upper or receiving end of the evaporator 15 isconnected to the Conduit by a Conduit 48 and an expansion valve 49 isconnected in the conduit 48. As shown in Figure 1 of the drawing, theconduit 48 is connected to the conduit 46 between the auxiliary tank 44and the valve 41. The return or lower end of the evaporator I 5 isconnected to the low pressure side of the compressor by a conduit 50.

The internal combustion engine l2 -is supported at the inner side of theevaporator I5, and is provided with a fan 5| for drawing air through theevaporator. scribed, the internal combustion engine is equipped with theusual ignition means 52, and is also provided with an electric startingmotor 53.

The air conditioning apparatus described above is controlled from acentral panel by the control circuit diagrammatically shown in Figure 2of the drawing. This control circuit comprises a threepole double-throwswitch 54 having a panel 55 provided with three push buttons indicatedin Figure 3 of the drawing by the reference characters 56, 51 and 58. Aswill presentlybe described, the apparatus may be operated to lower thetemperature of the atmosphere in the enclosure IS' by pushing the button55, and may be operated to raise the temperature of this atmosphere bypushing the button 51. The button 58 may be operated to diseontinu-e theoperation of the air conditioning apparatus. The operation of theapparatus may also be interrupted by a doublethrow switch 51' and thelatter, in turn, is auto- As will be more fuiy hereinafter dematicallyoperated by a thermostat (not shown) suitaby supported in the enclosureIS', so as to be responsive to variations in temperature of theatmosphere within the enclosure.

The switch 54 has three movable contact blades 59, 60 and Gi. Theterminal of the blade 59 is electrically connected to the terminal 62for the movable contact blade 63 of the switch 51' and the terminal 62is electrically connected to one side of a cranking limiter switch 64.The other side of the switch -84 is 'connected to the terminal B of avoltage regulator and is also connected to the negative pole of asuitable storage batte 'y 65. The switch blade 59 is alternatelyengageable with the fixed contacts 66 and 61. The fixed contact 56 isconnected to one end of a solenoid coil -68 and the opposite end of thecoil is connected to the positive pole of the battery through the ground59. The solenoid BB is operatively connected to .the valve 41 and isadaptedto open the valve 41 when the coil of the solenoid is energized.The terminal 61 of the switch 54 is electrically connected to one end ofthe solenoid coil 10 having the opposite end connected to the ground 69.The solenoid 10 is operatively connected to the valve 44 and is adaptedto open this valve when the coil of the solenoid is energized.

The center terminal\ of the movable contact blade 60 is eiectricallyconnected ?to one side of a safety switch 12 having the opposite sideconnected to one side of a pressure switch 13. The switch 13 has amovable contact 14 which alternately engages contacts 15 and 16. Thecontact 15 is eiectrically connected to the solenoid coil 11 of theStarter switch 18 and the contact 16 is electrically connected to thecenter terminal for the movable contact blade Bl of the switch 54.

The movable contact blade 50 alternately engages fixed contacts 11 and18. The contact 11 is electrically connected to the fixed contact 19 ofthe thermostat operated switch 51' and the contact 18 is connected tothe other terminal of the thermostat operated switch 51'. As statedabove, the center terminal of the movable contact blade SI iselectrically connected to the fixed contact 1'6 of the pressure switch13 and is also electrically connected to one end of a solenoid coil 8|having the opposite end connected to the ground 69. The solenoid sl isoperatively connected to a switch 82 having one side electricallyconnected to the terminal A of the voltage regulator and having theother side connected to the motor |1 for the fan IS.

The contact blade Gi alternately engages fixed contacts 83 and 84. Thefixed contact 83 is a blank contact and the contact 84 is electicallyconnected to one end of a. solenoid coil 85 having the opposite endconnected to the ground 69. The solenoid 85 is operatively connected toa switch 86 having one side connected to the terminal A or the voltageregulator and having the other side connected to the motor 38 for thecondenser fan 31.

Upon reference to Figura 2, it will be noted that one side of theStarter switch 18 is connected to the negative pole of the battery 85,and the other side of the Starter switch is connected to one end of thecoil 81 for the starting motor 53. The other end of the coil 81 isconnected to the terminal A of the voltage regulator. A second coil 88of the starting motor 53 is connected at one end to the ground 58 and isconnected at the other end to the terminal F of the voltage regulator.With lthis arrangement, the starting motor may be emoperation When it isdesired to cool the atmosphere within the enclosure IS', the louvres 23and 28 are opened. Manipulation of the control arm 30 to open thelouvres 28 swings the damper 36 toits closed position with respect tothe opening 34 and opens the opening si. Also. the thermostatic switch51' is in a position wherein the movable contact 63 engages the fixedcontact 80, so that the fixed contact 18 of the switch 54 is energized.The switch 54 is then operated by pressing the push button 56, with theresult that the movable contacts 59, 60 and SI are respectively engagedwith the fixed contacts 66, 18 and 84.

As a result of the foregoing, the solenoid 68 is energized to open thevalve 41, and the solenoid is deenergized to permit the valve dd toclose. The safety switch 72 is normally closed by the spring 92, so thatthe ignition coil 90 is energized. Also, the pressure switch 14 is in a.position wherein the fixed contact '15 is energized, so that the coil Tiof the starter switch 18 is also energized. As soon as the internalcombustion engine is started, the pressure built up by the oil pump ofthe engine operates the pressure switch 13 to energize the fixed contact75 and thereby closes the circuit to the motor I'l for the fan IE. Itwill further be noted that the contact 85 of the switch i 5@ isenergized, and as a result the switch 86 is closed by the solenoid 85 tooperate the condenser fan motor 38.

It has been briefiy stated above that the pressure switch 13 is operatedby the oil pressure within the internal combustion engine. In thisconnection, attention is again directed to Figure 2 of the drawingwherein it will be noted that the movable contact 'M of the switch isconnected to an expansible chamber 93 *and the expansible chamber inturn is connected to the oil pump of the engine. The arrangement is suchthat when the engine is started, pressure is built up in the expansiblechamber 93, and as the latter expands, it moves the switch contact 'idfrom the position shown in Figure 2 in engagement with the contact ?5 toa position in engagement with the contact '56 to energize the solenoidal. It was also stated above that the safety switch l? is normally inits closed position. This safety switch is connected in series with thepressure switch lt' and also comprises an expansible chamber t. Thechamber dt is connected to the condenser 53 so that if the pressure inthe condenser should approach an abnormal quantity, the switch l' isautomatically opened by expansion of the chamber Q t.

The compressor l l is, of course, operated by the engine and dischargesthe gaseous refrigerating medium into the upper end of the condenser '53through the Conduit 39. The gaseous refrigerating medium is condensed bythe air circulated through the condenser and the resulting high pressureliquid lows into the receiver tank t). The liquid refrigerant flows fromthe receiver tank t through the conduit 4| to the expansion valve %2. Asthe refrigerant passes through the expansion valve 42, it expands into alow pressure mixture of gas and liquid. This mixture is discharged intothe receiving or upper end of the heat exchange unit ll and, as themixture passes downwardly through the latter.it absorbs heat from the'air being blown or forced through the heat exchange unit by the fan IS.As the mixture absorbs heat from the atmosphere within the enclosure ie,it is converted into a vapor and is still at relatively low pressure.The vapor 'is discharged from the heat exchange unit M through theconciuit 65 to the auxiliary receiving tank u and passes through theconduit 46 to the low pressure side of the compressor Il. As statedabove, the vaive 47 has previouslybeen opened, so that it does notrestrict the passage of the vapor from the tani;` 44 to the compressor.In this connection it is pointed out that the expa sion valve 49 isrestricted. so that when the valve 61 is open, very little or no gasfiows to the evaporator !5 on the suctipn stroke of the compressor.Therefore the considered as inoperative during the cooling cycle and theheat exchange unit i may be considered as the evaporator.

It will also be noted that whenever the apparatus is operated on thecooling cycle, the fan 5! draws air through the opening 26 and throughthe evaporator 15. This air is directed in heat conducting relationshipto the internal combustion engine to cool the same and is thendischarged into the duct`32 with the exhaust gases or products ofcombustion. The air mixed with the products of combustion is dischargedout of the compartmnt I 8 through the opening ai.

The apparatus operates on the cooling cycle until the temperature withinthe enclosure IE' drops below a predetermined value determined by asuitable thermostat within the enclosure. This thermostat in turnoperates the switch 5'5', and the latter is connected in the circuitshown in Figure 2 ot' the drawing in such a manner that it automaticallystarts and stops the internal combustion engine in accordance withtemperature fluctuations within the enclosure.

Assuming now that it is desired to heat the atmosphere within theenclosure IS', the operator merely depresses the push button 57 on thecontrol switch Et. Also, the control arm 24 is operated to close thelouvres 23 and the control arm 30 is operated to close the louvres za.Clos- 'ng of the louvres 28 effects a swinging movement of the damper 36to its dottcd line position shown in Figure 1 of the drawing wherein theopening 3! is closed and the duet 32 communicates with the space betweenthe evaporator !5 and the louvres 28. i i

operation of the switch 5:3 by manipulating the push button 51 energizesthe solenoid coil ?d to open the valve &ti and, of course, deenergizesthe solenoid coil '68 to permit the valve t? to close. Also, the movablecontact 63 of the switch 51' engages the stationary contact '79 toenergize the latter, so that the ignition circuit and Starter motor areoperated in the same manner as previously described in connection withthe cooling cycle. However, it is to be noted that the solenoid isdeenergized so that the switch 88 is open, and operation of thecondenser fan t'i is discontinued.

When the motor is started, the compressor ti discharges gaseousrefrigerant under high pressure through the conduit 39 to the upper endof evaporator !5 may be eirculated through the eondenser !3. Thiseondenser, however, is inoperative due to the fact that no air is beingthe same, and as a result, the rerigerant passes through the tank 40 andthrough the bypass 43 to the receiving end of the heat exchange unit l4.In this connection it will be noted that the valve 44 is open to permitrelatively free flow of refrigerant to the heat exchange unit, and sincethe expansion valve 42 is restricted, very little or no flow takes placein the conduit 4 I As the gascous refrigerating medium passes throughthe heat exchange unit l4, it gives up heat to the air being blownthrough the heat exchange unit by the'fan IS, and in this respect, theheat exchange unit may be eonsidered as a eondenser. The condensedrefrigerant is discharged from the heat exchange unit through theconduit 45 into the auxiliary tank 44 and since the valve 41 is closed,the refrigerant passes through the conduit 48 and expansion valve 49 tothe upper end of the evaporator !5. As the refrigerant passes throughthe expansion valve 49, it is expanded, and the resulting low pressuremixture passes through the evaporator to the low pressure side of thecompressor. As the mixture fiows through the evaporator, it absorbs heatfrom the air and exhaust gases which are circulated through theevaporator by the fan 5! of the engine. The air passing through theevaporator is cooled and is then conducted into heat conductingrelationship to the internal combustion engine. In this connection itwill be noted that the opening IS establishes permanent communicationbetween the interier of the compartment and the atmosphere, so thatexhaust gases cannot build up a pressure within the compartment. The airfor mixture in the carburetor may be drawn into the compartment througha suitable fiexible hose (not shown herein) When the apparatus isOperating on the cooling cycle, it may be necessary at times to defrostthe heat exchange unit I4, because the latter is Operating as anevaporator under such conditions. When it is desired to defrost the heatexchange unit 14, the operator merely depresses the push button 58 orstop button on the switch 54 to discontinue the cooling cycle. Thebutton 51 on the switch 54 is then operated to initiate the heatingcycle, and the apparatus is operated on the heating cycle until completedefrosting has been accompiished. It may he pointed out at this timethat it is not necessary to disturb the louvres 23 and 28 during thedefrosting operation, since enough heat will be absorbed from the airbeing drawn through the opening 3| and ev-aporator !5 by the engine fanSI.

What I claim as my invention is:

1. An electric control circuit for air conditioning apparatus having arefrigerant compressor, a eondenser for the compressed refrigerant, aheat exchange unit having a fluid connection with the low pressure sideof the compressor, an e'xpanslon valvein the fluid connection betweenthe eondenser and evaporator, means for forcing air through theeondenser to condense the refrigerant passing therethrough, said meansincluding a fan and an electric motor for Operating the fan, a normallyclosed valve controlled bypass extending around the expansion valve,said control circuit comprising a switch for the motor, a solenoidoperatively connected to the bypass valve, a master switch operable toenergize the solenoid to open the bypass valve, and means for openingthe fan motor switch in response to operation of the master switch toopen the bypass valve.

2. An electric control circuit for air conditioning apparatus having arefrigerant compressor, a eondenser for the compressed rerigerant, aheat exchange unit having a fluid connection with the eondenser forreceiving refrigerant from the latter and having a fluid connection withthe low pressure side of the compressor, an expansion valve in the fluidconnection between the condenser and evaporator, a valve controlledbypass extending around the expansion valve, a second normally closedvalve in the fluid connection bei tween the heat exchange unit and lowpressure side of the compressor, said control circuit comprising a pairof solenoids respectively operatively connected to the valves, 'and amaster switch in circuit with the solenoids and having means forselectively Operating the valves to their open positions.

3. An electric control circuit for air conditioning apparatus having arefrigerant compressor, a condenser for the compressed rerigerant, aheat exchange unit having a fluid connection with the eondenser forreceivng refrigerant from the latter and having a fluid connection withthe low pressure side of the compressor, an expansion valve in the fluidconnection between the condenser and evaporator, means for orcing airthrough the eondenser to condense the refrigerant passing therethrough,said means including a fan and an electric motor for Operating the fan,a normally closed valve controlled bypass extending around the expansionvalve, a second normally closed valve in the fluid connection betweenthe heat exchange unit and low pressure side of the compressor, saidcontrol circuit comprising a pair of solenoids respectively operativelyconnected to the valves, a master switch in circuit with the solenoidsand having means for selectively Operating the valves to their openpositions, and means for opening the fan motor switch in response tooperation of the master switch to open the bypass valve.

4. A control circuit for air conditioning apparatus having a refrigerantcompressor, an internal combustion engine for Operating the compressor,a heat exchange unit including a fan and an electric motor for Operatingthe fan, said control circuit comprising a source of electrical energy,an electric starting motor for the engine, a switch connectng thestarting motor to the source of electrical energy, a solenoid foroperating the starter switch, a second switch for operating the fanmotor, a second solenoid for operating the fan motor switch, a controlswitch for connectng the solenoids to the source of electrical energy, apressure switch connected in the control circuit between the controlswitch and the solenoids and normally positioned to connect the startingswitch solenoid to the source of electrical energy, and means responsiveto the operation of the engine to operate the pressure switch todisconnect the starting switch solenoid from the source and to connectthe second solenoid to said source.

5. A controlcircuit for air conditioning apparatus having a refrigerantcompressor. an internal combustion engine for Operating the compressor,an ignition circuit for the engine, said control circuit comprising asource of electrical energy, a control switch for connectng the ignitioncircuit to the source of electrical energy, and a safety switch betweenthe control switch and the ignition circuit op'erable to open theignition circuit in response to abnormal pressures in a part of the airconditioning apparatus.

6. A control circuit for air conditioning apparatus having e refrigemntcompressor, an internal combustion engine for Operating the compressorand having an ignition circuit, a. condenser for the compressedrefrigerant, said control circuit comprising a source of electricalenergy, a. control switch for connecting the ignition circuit to thesource of electricai energy, and a safety switch between the controlswitch and the ignition circuit cperable to open the ignition circuit inresponse to abnormal pressures in the condenser of the apparatus.

7. A control circuit for air conditioning apparatus having a refrigerantcompressor, a condenser connected to the compressor, an internalcombustion engine for Operating the compressor and having an ignitioncircuit, said control circuit comprising a. source of eiectrica energy,a con- 20 trol switch for connecting the ignition circuit to 'the sourceof electrical energy, means responsive to the operation of the enginefor moving the control switch to its open position, a safety switchbetween the control switch and the ignition cir- 25 Number cuit, andmeans responsive to a predetermined pressure rise in the condenser forOperating the safety switch to open said ignition circuit.

8. A control circuit for air conditioning apparatus having a refrigerantcompressor, a con- 30 2,387,604

denser connected to the compressor, an internal combustion engine forOperating the compressor and having an ignition circuit, a, heatexchange unit including a fan and an electric motor for Operating thefan, said control circuit comprising e source of electrical energy, anelectric starting motor for the engine included in the ignition circuit,a switch in the ignition circuit for connecting the letter to a sourceof electrical eneray, a. second switch in the control circuit forOperating the !en motor, means responsive to initial starting of theinternal combustion engine for Operating the first named switch to openthe ignition circuit and to close the second named switch to operntesaid fan motor, and a. safety switch for opening the ignition circuit inresponse to a. predetermined pressure rise in the condenser.

HENRY O. KIRKPATRICK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 2,039,240 F'rese Apr. 28, 193642,187,397 Goggins Jan. 16, 1940 2,281,770 I-Ioesel May 5, 19422,344,215 soling Mar. 14, 1944 Newton Oct. 23, 1945

